Data nullification device for nullifying digital content recorded on a recording medium, after the digital content has been reproduced, a predetermined time period has passed since the recording of the digital content, or the digital content has been moved to another recording medium

• US 20020126843A1
• Filed: 02/06/2002
• Published: 09/12/2002
• Est. Priority Date: 02/15/2001
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Motohashi, Yoshihiko, Ito, Yoshikatsu, Miyazaki, Masaya, Murase, Kaoru
• Granted Patent: US 7,493,662 B2
• Time in Patent Office: Days
• US Class Current: 380/201
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00195 using a device identifier associated with the player or recorder, e.g. serial numbers of playback apparatuses or MAC addresses
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00507 wherein consecutive physical data units of the record carrier are encrypted with separate encryption keys, e.g. the key changes on a cluster or sector basis
• CPC Class Codes: G11B 20/00666 involving a step of erasing or nullifying data, e.g. data being overwritten with a random string
• CPC Class Codes: G11B 20/00753 wherein the usage restriction limits the number of copies that can be made, e.g. CGMS, SCMS, or CCI flags
• CPC Class Codes: G11B 20/00789 wherein the usage restriction limits the number of functional copies, which can be accessed at a time, e.g. electronic bookshelf concept, virtual library, video rentals or check-in/check out
• CPC Class Codes: G11B 20/10 Digital recording or reproducing

Abstract

A data nullification device for nullifying target data recorded on a recording medium is provided. The target data is made up of a plurality of data blocks. A judging unit judges, in units of data blocks, whether the target data needs to be nullified. A nullifying unit nullifies, when a predetermined number of data blocks are judged as needing to be nullified or when one or more data blocks whose total amount of data reaches a predetermined amount are judged as needing to be nullified, the judged data blocks.

Claims

1. A data nullification device for nullifying target data recorded on a recording medium, the target data being made up of a plurality of data blocks, the data nullification device comprising:

a judging unit operable to judge, for each data block recorded on the recording medium, whether the data block needs to be nullified; and

a nullifying unit operable to nullify, when a predetermined number of data blocks are judged as needing to be nullified or when one or more data blocks whose total amount of data reaches a predetermined amount are judged as needing to be nullified, the judged data blocks.

2. The data nullification device of claim 1,

wherein the recording medium stores sequence information that shows a sequence in which the plurality of data blocks were recorded onto the recording medium, and

the judging unit judges, in succession, the plurality of data blocks in the sequence shown by the sequence information, as needing to be nullified.

3. The data nullification device of claim 2,

wherein the target data is data which is continuously transmitted from an external device and recorded on the recording medium,

the data nullification device further comprises:

a receiving unit operable to receive data from the external device, and

having set the received data as a new data block, the nullifying unit writes the new data block to a recording area on the recording medium that stores a data block which is judged as needing to be nullified, to nullify the recorded data block and at the same time record the new data block.

4. The data nullification device of claim 3,

wherein each data block has a length corresponding to a fixed transmission time period, and

a specified number of recording areas which are each used as a recording area of a data block are reserved on the recording medium.

5. The data nullification device of claim 4,

wherein if the length corresponding to the fixed transmission time period is variable and if part of the recorded data block remains even after the new data block is written, the nullifying unit further writes arbitrary data over the part of the recorded data block.

6. The data nullification device of claim 4,

wherein if there is not a new data block which is to be recorded, the nullifying unit writes arbitrary data to the recording area.

7. The data nullification device of claim 2, further comprising:

a utilizing unit operable to utilize the target data recorded on the recording medium, in units of data blocks,

wherein the judging unit further judges that each data block which was utilized by the utilizing unit needs to be nullified.

8. The data nullification device of claim 7,

wherein the target data is content data which is transmitted from an external device and recorded on the recording medium,

the content data is accompanied with copy control information showing whether copying of the content data is permitted or prohibited,

the utilizing unit reproduces the content data recorded on the recording medium, in units of data blocks, and

only if the copy control information accompanying the content data shows that the copying of the content data is prohibited, the judging unit judges that each data block which was reproduced by the utilizing unit needs to be nullified.

9. The data nullification device of claim 1,

wherein the recording medium stores time limit information showing a recording time limit of each data block recorded on the recording medium, the recording time limit being a time limit after which retention of the data block on the recording medium is prohibited,

the judging unit judges that each data block whose recording time limit is reached needs to be nullified, based on the time limit information, and

whenever any data block is judged as needing to be nullified because a recording time limit of the data block is reached, the nullifying unit nullifies the data block irrespective of whether the predetermined number of data blocks are judged as needing to be nullified or whether one or more data blocks whose total amount of data reaches the predetermined amount are judged as needing to be nullified.

10. The data nullification device of claim 9, further comprising:

a utilizing unit operable to utilize the target data recorded on the recording medium, in units of data blocks,

wherein the judging unit further judges that each data block which was utilized by the utilizing unit needs to be nullified.

11. The data nullification device of claim 10,

wherein the target data is content data which is transmitted from an external device and recorded on the recording medium,

the content data is accompanied with copy control information showing whether copying of the content data is permitted or prohibited,

the utilizing unit reproduces the content data recorded on the recording medium, in units of data blocks, and

only if the copy control information accompanying the content data shows that the copying of the content data is prohibited, the judging unit judges that each data block which was reproduced by the utilizing unit needs to be nullified.

12. The data nullification device of claim 1, further comprising:

a utilizing unit operable to utilize the target data recorded on the recording medium, in units of data blocks,

wherein the judging unit judges that each data block which was utilized by the utilizing unit needs to be nullified.

13. The data nullification device of claim 12,

wherein the target data is content data which is transmitted from an external device and recorded on the recording medium,

the content data is accompanied with copy control information showing whether copying of the content data is permitted or prohibited,

the utilizing unit reproduces the content data recorded on the recording medium, in units of data blocks, and

only if the copy control information accompanying the content data shows that the copying of the content data is prohibited, the judging unit judges that each data block which was reproduced by the utilizing unit needs to be nullified.

14. The data nullification device of claim 12,

wherein the target data is accompanied with copy control information showing whether copying of the target data is permitted or prohibited,

the utilizing unit records the target data recorded on the recording medium, to another recording medium, in units of data blocks, and

only if the copy control information accompanying the target data shows that the copying of the target data is prohibited, the judging unit judges that each data block on the recording medium which was recorded by the utilizing unit needs to be nullified.

15. The data nullification device of claim 1,

wherein the nullifying unit destroys all parts of a data block which is judged as needing to be nullified.

16. The data nullification device of claim 1,

wherein the nullifying unit destroys at least a part of a data block which is judged as needing to be nullified, the part of the data block being necessary to utilize remaining parts of the data block.

17. The data nullification device of claim 16,

wherein the target data is MPEG data including I pictures, and

the part of the data block necessary to utilize the remaining parts of the data block is an I picture.

18. The data nullification device of claim 16,

wherein the target data is MPEG data including I pictures, and

the part of the data block necessary to utilize the remaining parts of the data block is a first sector of an I picture.

19. The data nullification device of claim 16,

wherein when the data nullification device does not have an enough processing capacity, the nullifying unit destroys only the part of the data block necessary to utilize the remaining parts of the data block.

20. The data nullification device of claim 19,

wherein the nullifying unit destroys the remaining parts of the data block within a range where a processing capacity of the data nullification device allows.

21. The data nullification device of claim 19, further comprising:

a destroying unit operable to destroy remaining parts of data blocks which were not destroyed by the nullifying unit, when the data nullification device has an enough processing capacity.

22. The data nullification device of claim 1,

wherein each data block recorded on the recording medium has been encrypted using an individual encryption key,

a decryption key for decrypting the encrypted data block is stored on the recording medium, and

the nullifying unit destroys at least a decryption key corresponding to a data block which is judged as needing to be nullified.

23. The data nullification device of claim 22, further comprising:

an acquiring unit operable to acquire the target data in an encoded form;

a decoding unit operable to decode the encoded target data using a user key which has been provided to authorized users in advance, to obtain the target data;

a key generating unit operable to generate an arbitrary encryption key and a decryption key corresponding to the encryption key, for each data block of the target data;

a data encrypting unit operable to encrypt the data block using the encryption key so that the encrypted data block can be decrypted using the corresponding decryption key;

a key encrypting unit operable to encrypt the decryption key using an identifier unique to the data nullification device; and

a recording unit operable to record the encrypted data block and the encrypted decryption key onto the recording medium.

24. The data nullification device of claim 23, wherein at least the decoding unit, the key generating unit, the data encrypting unit, and the key encrypting unit are contained in a single semiconductor chip.

26. The data nullification program of claim 25,

wherein the recording medium stores sequence information that shows a sequence in which the plurality of data blocks were recorded onto the recording medium, and

the judging step judges, in succession, the plurality of data blocks in the sequence shown by the sequence information, as needing to be nullified.

27. The data nullification program of claim 26,

wherein the target data is data which is continuously transmitted from an external device and recorded on the recording medium,

the data nullification program further having the computer execute the step of:

receiving data from the external device,

wherein having set the received data as a new data block, the nullifying step writes the new data block to a recording area on the recording medium that stores a data block which is judged as needing to be nullified, to nullify the recorded data block and at the same time record the new data block.

28. The data nullification program of claim 26, further having the computer execute the step of:

utilizing the target data recorded on the recording medium, in units of data blocks,

wherein the judging step further judges that each data block which was utilized in the utilizing step needs to be nullified.

29. The data nullification program of claim 25,

wherein the recording medium stores time limit information showing a recording time limit of each data block recorded on the recording medium, the recording time limit being a time limit after which retention of the data block on the recording medium is prohibited,

the judging step judges that each data block whose recording time limit is reached needs to be nullified, based on the time limit information, and

whenever any data block is judged as needing to be nullified because a recording time limit of the data block is reached, the nullifying step nullifies the data block irrespective of whether the predetermined number of data blocks are judged as needing to be nullified or whether one or more data blocks whose total amount of data reaches the predetermined amount are judged as needing to be nullified.

30. The data nullification program of claim 29, further having the computer execute the step of:

utilizing the target data recorded on the recording medium, in units of data blocks,

wherein the judging step further judges that each data block which was utilized in the utilizing step needs to be nullified.

31. The data nullification program of claim 25, further having the computer execute the step of:

utilizing the target data recorded on the recording medium, in units of data blocks,

wherein the judging step judges that each data block which was utilized in the utilizing step needs to be nullified.

32. The data nullification program of claim 25,

wherein the nullifying step destroys all parts of a data block which is judged as needing to be nullified.

33. The data nullification program of claim 25,

wherein the nullifying step destroys at least a part of a data block which is judged as needing to be nullified, the part of the data block being necessary to utilize remaining parts of the data block.

34. The data nullification program of claim 25,

wherein each data block recorded on the recording medium has been encrypted using an individual encryption key,

a decryption key for decrypting the encrypted data block is stored on the recording medium, and

the nullifying step destroys at least a decryption key corresponding to a data block which is judged as needing to be nullified.

36. The data nullification method of claim 35,

wherein the recording medium stores sequence information that shows a sequence in which the plurality of data blocks were recorded onto the recording medium, and

the judging step judges, in succession, the plurality of data blocks in the sequence shown by the sequence information, as needing to be nullified.

37. The data nullification method of claim 36,

wherein the target data is data which is continuously transmitted from an external device and recorded on the recording medium,

the data nullification method further comprising the step of:

receiving data from the external device,

wherein having set the received data as a new data block, the nullifying step writes the new data block to a recording area on the recording medium that stores a data block which is judged as needing to be nullified, to nullify the recorded data block and at the same time record the new data block.

38. The data nullification method of claim 36, further comprising the step of:

utilizing the target data recorded on the recording medium, in units of data blocks,

wherein the judging step further judges that each data block which was utilized in the utilizing step needs to be nullified.

39. The data nullification method of claim 35,

wherein the recording medium stores time limit information showing a recording time limit of each data block recorded on the recording medium, the recording time limit being a time limit after which retention of the data block on the recording medium is prohibited,

the judging step judges that each data block whose recording time limit is reached needs to be nullified, based on the time limit information, and

whenever any data block is judged as needing to be nullified because a recording time limit of the data block is reached, the nullifying step nullifies the data block irrespective of whether the predetermined number of data blocks are judged as needing to be nullified or whether one or more data blocks whose total amount of data reaches the predetermined amount are judged as needing to be nullified.

40. The data nullification method of claim 39, further comprising the step of:

utilizing the target data recorded on the recording medium, in units of data blocks,

wherein the judging step further judges that each data block which was utilized in the utilizing step needs to be nullified.

41. The data nullification method of claim 35, further comprising the step of:

utilizing the target data recorded on the recording medium, in units of data blocks,

wherein the judging step judges that each data block which was utilized in the utilizing step needs to be nullified.

42. The data nullification method of claim 35,

wherein the nullifying step destroys all parts of a data block which is judged as needing to be nullified.

43. The data nullification method of claim 35,

wherein the nullifying step destroys at least a part of a data block which is judged as needing to be nullified, the part of the data block being necessary to utilize remaining parts of the data block.

44. The data nullification method of claim 35,

wherein each data block recorded on the recording medium has been encrypted using an individual encryption key,

a decryption key for decrypting the encrypted data block is stored on the recording medium, and

the nullifying step destroys at least a decryption key corresponding to a data block which is judged as needing to be nullified.

25. A data nullification program for nullifying target data recorded on a recording medium, the target data being made up of a plurality of data blocks, the data nullification program having a computer execute the steps of:

judging, for each data block recorded on the recording medium, whether the data block needs to be nullified; and

nullifying, when a predetermined number of data blocks are judged as needing to be nullified or when one or more data blocks whose total amount of data reaches a predetermined amount are judged as needing to be nullified, the judged data blocks.

35. A data nullification method for nullifying target data recorded on a recording medium, the target data being made up of a plurality of data blocks, the data nullification method comprising the steps of:

judging, for each data block recorded on the recording medium, whether the data block needs to be nullified; and

nullifying, when a predetermined number of data blocks are judged as needing to be nullified or when one or more data blocks whose total amount of data reaches a predetermined amount are judged as needing to be nullified, the judged data blocks.